Work around for HDMI audio output rediscovering transistion loss.

chromeos/audio/cras_audio_handler.h

Index: chromeos/audio/cras_audio_handler.h
diff --git a/chromeos/audio/cras_audio_handler.h b/chromeos/audio/cras_audio_handler.h
index 633e30a33a7a2d5d9b4729f747479f23c668b79c..10c77a471da34484a652cd488124cccf26c5613d 100644
--- a/chromeos/audio/cras_audio_handler.h
+++ b/chromeos/audio/cras_audio_handler.h
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "base/timer/timer.h"
 #include "chromeos/audio/audio_device.h"
 #include "chromeos/audio/audio_pref_observer.h"
 #include "chromeos/dbus/audio_node.h"
@@ -188,6 +189,15 @@ class CHROMEOS_EXPORT CrasAudioHandler : public CrasAudioClient::Observer,
   // Enables error logging.
   virtual void LogErrors();
 
+  // If necessary, sets the starting point for re-discovering the active HDMI
+  // output device caused by device entering/exiting docking mode, HDMI display
+  // changing resolution, or chromeos device suspend/resume. If
+  // |force_rediscovering| is true, it will force to set the starting point for
+  // re-discovering the active HDMI output device again if it has been in the
+  // middle of rediscovering the HDMI active output device.
+  virtual void SetActiveHDMIOutoutRediscoveringIfNecessary(
+      bool force_rediscovering);
+
  protected:
   explicit CrasAudioHandler(
       scoped_refptr<AudioDevicesPrefHandler> audio_pref_handler);
@@ -293,6 +303,16 @@ class CHROMEOS_EXPORT CrasAudioHandler : public CrasAudioClient::Observer,
   // Removes |node_id| from additional active nodes.
   void RemoveActiveNodeInternal(uint64_t node_id, bool notify);
 
+  void UpdateAudioAfterHDMIRediscoverGracePeriod();
+
+  bool IsHDMIPrimaryOutputDevice() const;
+
+  void StartHDMIRediscoverGracePeriod();
+
+  bool hdmi_rediscovering() const { return hdmi_rediscovering_; }
+
+  void SetHDMIRediscoverGracePeriodForTesting(int duration_in_ms);
+
   enum DeviceStatus {
     OLD_DEVICE,
     NEW_DEVICE,
@@ -328,6 +348,11 @@ class CHROMEOS_EXPORT CrasAudioHandler : public CrasAudioClient::Observer,
   // Failures are not logged at startup, since CRAS may not be running yet.
   bool log_errors_;
 
+  // Timer for HDMI re-discovering grace period.
+  base::OneShotTimer<CrasAudioHandler> hdmi_rediscover_timer_;
+  int hdmi_rediscover_grace_period_duration_in_ms_;
+  bool hdmi_rediscovering_;
+
   base::WeakPtrFactory<CrasAudioHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CrasAudioHandler);